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SCIENCE 



[N. S. Vol. XXVII. No. 682 



conditi&n; since the distribution of native 

 plants is a matter of secular or millennial, and 

 not merely of existing conditions. The inter- 

 pretation of these analyses will require no mere 

 routine consideration of percentages, but must 

 be correlated with the physical composition; 

 inasmuch as a light sandy oil requires much 

 less lime to support a calciphile flora than a 

 heavy clay;" and the same is more or less true 

 of other ingredients. It should not be for- 

 gotten, however, that quite a large number of 

 plants have long ago been shown to be prac- 

 tically indifferent to the absence or presence 

 of lime. 



Again, the paludal or peaty nature of the 

 ground or locality requires consideration. 

 The mere presence of a certain proportion of 

 lime may be wholly ineffective in bringing 

 about a calciphile flora if humic acids present 

 produce an acid condition of the soil mass. 

 On the other hand, if a calcareous weathering- 

 product is exposed to continuous leaching, as 

 may easily happen on the summits of hills 

 bearing abundant vegetation, the lime carbon- 

 ate may be almost wholly leached out, and is- 

 lands of calcifuge plants will then be found 

 in calciphile territory. The calcareous wash- 

 ings, on the contrary, will impregnate the 

 lower ground, which is always more calcareous 

 than the higher slopes; and so a calciphile 

 flora may, and very commonly does, occur 

 where no obvious source of lime exists in the 

 uplands. 



Fernald rightly considers the hornhlendic 

 rocks as sources of calcareous soils; yet 

 in the Hawaiian islands the black lavas, 

 which weather into spongy iron ores used 

 as soils, are almost fully leached of the lime 

 that forms so large a proportion of both 

 pyroxene \and hornblende, by the abundant 

 rains of the tropics ; while the almost identical 

 basalts on the Pacific coast produce cal- 

 careous soils, with a uniformly calciphile 

 flora, on account of the deficient rainfall. 



It is thus obvious that not only the original 

 soil-forming rocks, but also the climatic con- 

 ditions and the " lay of the land " must be 

 considered in forecasting the plant-geography 



' See " Soils," etc., pp. 494-497, 367 ff. 



of any region. The failure to do this and the 

 physiologically erroneous definition of cal- 

 careous soils as " aoils that effervesce with 

 acids," has brought about the confusion which 

 appears in the works of Schimper, Contejean 

 and others, as to the causes of plant distribu- 

 tion. 



Fernald's paper is provided with copious 

 references to sources of information in rela- 

 tion to the occurrence of rocks and plants, 

 as vouchers for his conclusions. On the other 

 hand, his references to cognate work done 

 in Europe as well as in this country, are 

 somewhat scanty, being probably left for the 

 final publication of his results. 



His present conclusions are succinctly set 

 forth in the following quotations from p. 170 

 of the paper : 



After comparing the floras of three areas 

 located not far apart and under identical con- 

 ditions of exposure and precipitation, he says : 



Precipitation and exposure are, then, of only 

 minor importance in determining the localized dis- 

 tribution of our alpine plants. 



In attempting to account for the peculiarities 

 of plant distribution, much stress has of late been 

 laid upon the degree of fineness or coarseness of 

 soils, and their water content. But to those inti- 

 mate with the occurrence of our alpine plants 

 these factors, again, seem of secondary impor- 

 tance. For instance, Cystopteris montana on Mt. 

 Albert grows in equal abundance on the firm and 

 steep amphibolite cliffs and in the deep, fine and 

 (water-) saturated alluvium of mountain streams. 

 Selaginella selaginoides, abundant in the wet, 

 mossy bogs of Bonaventure and Gasp6 counties, 

 Quebec, is quite as much at home in the well- 

 drained alpine meadows, or in the crevices of 

 either wet or dry rocks; in the latter situation 

 becoming stiflfer and more stocky than in deep 

 shade or moisture. Zygadenus chloranthus is ap- 

 parently indifi'erent whether it is in the crevices 

 of sunbaked rock, on cold cliffs, in river alluvium 

 or on wet bogs. Similarly, many other members 

 of the flora characteristic of the areas classed as 

 group 2 (calciphile) grow in wet or dry, fine or 

 coarse soils. 



The distinctive plants of groups 1 and 3 (potas- 

 sic and magnesian) likewise show a remarkable 

 indifference to the coarseness or fineness, the dry- 

 ness or saturation of their supporting soils . . . 

 seem equally at home in crevices of sun-baked or 



